<!DOCTYPE html>
<html lang="en">

<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	<style>
		.left {
			width: 200px;
			height: 100vh;
			background-color: lightcoral;
			float: left;
		}

		.right {
			/* width: auto; */
			/* margin-left: 200px; */
			height: 100vh;
			background-color: blueviolet;
		}
	</style>
</head>

<body>
	<div class="left"></div>
	<div class="right"></div>
</body>

</html>